The Effects of Alcohol on The Body's Major Systems

Dietary Guidelines for Alcohol Consumption

Published by the US Office of Health Promotion and Disease Prevention, the 2015-2020 Dietary Guidelines for Americans defines “moderate drinking” as 1 drink per day in women and 2 drinks per day in men.<sup>5</sup> Regardless of any comorbid conditions, the effects of alcohol consumption can include reduced inhibitions, motor impairment, respiratory distress, coma, and death.<sup>6</sup>

Type 1 and Type 2 Diabetes

Research published in <i>Diabetes Care</i> suggests that decreasing alcohol consumption can have a beneficial effect in type 2 diabetes;<sup>7,8</sup> specifically, that it may result in decreased fasting insulin and hemoglobin A1c (HbA1c)7 and diabetes risk reduction in women.<sup>8</sup> An abstract presented at the 2016 Annual Meeting of the Endocrine Society found that heavy alcohol consumption also had no impact on diabetes risk.<sup>9</sup> In type 1 diabetes, however, alcohol has been associated with acute hypoglycemia, with even moderate alcohol consumption “predisposing patients to hypoglycemia after breakfast the next morning.”<sup>10</sup> Researchers from Yale University School of Medicine and the Royal Bournemouth Hospital in the United Kingdom caution that people with type 1 diabetes should be made aware of this risk in order to take the appropriate preventative measures. The American Diabetes Association (ADA) supports emphasizing the importance of alcohol taken in moderation,<sup>11</sup> encouraging people with diabetes to drink cautiously and regularly check blood glucose levels before, during, and up to 24 hours after drinking.

Osteoporosis and Bone Health

Regular alcohol consumption presents its own set of risks related to bone health and the development of osteoporosis. According to the US National Institute of Health (NIH) Osteoporosis and Related Bone Diseases National Resource Center, excessive alcohol consumption can interfere with the balance of calcium and vitamin D, as well as hormone deficiencies, lower testosterone in men, irregular menstrual cycles in women, and elevated cortisol, which increases bone breakdown.<sup>12</sup> In addition, alcohol effects balance and gait — people with alcoholism fall more frequently than people without alcoholism.<sup>12</sup> Specifically, hip and vertebral fractures have been linked to heavy alcohol consumption.<sup>12</sup> According to the NIH, abstaining from alcohol is the best strategy to prevent alcohol-induced bone loss.<sup>12</sup> However, a well-balanced diet, vitamin D supplementation, and exercise can all mitigate the effects of alcohol.<sup>12</sup> This population can also consider a bone mineral density test as a way to detect osteoporosis before a fracture occurs.<sup>12</sup>

Hypo- and Hyperthyroidism

Like diabetes, moderate alcohol consumption has been found to have a protective effect on autoimmune disorders<sup>13</sup> — for example, decreasing a person’s risk of developing hypothyroidism. In addition, research published in <i>Clinical Endocrinology</i> found a link between alcohol consumption and risk reduction for Graves’ disease.<sup>14</sup> However, other studies have identified multiple effects that alcohol has on the hypothalmopituitary axis — for example, suppression of thyroid function through cellular toxicity and a decrease in peripheral thyroid hormones.15 In 2015, <i>Alcohol and Alcoholism</i><sup>16</sup> published a study that explored the relationship between the thyroid axis and alcohol-seeking behavior in patients with alcohol dependence. The investigators identified correlations between thyroid stimulating hormone; free triiodothyronine; and the questionnaires used to measure alcohol cravings and anxiety, depression, and aggression, indicating that, if confirmed in larger samples, the thyroid axis “might represent a biomarker of alcohol craving and drinking.”

Alcohol Consumption in Pregnancy

The Centers for Disease Control and Prevention (CDC) cautions that there is “no known safe amount of alcohol use during pregnancy.”<sup>17</sup> Drinking while pregnant can cause miscarriage; stillbirth; and a number of fetal alcohol spectrum disorders including low body weight, poor coordination, memory and attention issues, and learning disabilities, among others.<sup>17</sup> A 2010 study from the <i>International Journal of Environmental Research and Public Health</i> reviewed long-term outcomes in children exposed to alcohol during pregnancy.<sup>18</sup> The investigators noted that early detection of intrauterine alcohol exposure may “enable effective social and educational intervention programs,”<sup>18</sup> providing appropriate support to both mothers and children.

Neurological Effects of Alcohol Use and Abuse

Neurological research has found that stroke mortality and alcohol consumption are related: a study published in the <i>International Journal of Cardiology</i><sup>19</sup> identified a J-shaped association between stroke morbidity and alcohol intake, while a study published in <i>Stroke</i><sup>20</sup> found that heavy drinking in midlife can “predominate over well-known risk factors” for stroke, including hypertension and diabetes until age 75. As a result, alcohol consumption should be considered an age-varying risk factor. In a similar manner, research has highlighted the negative consequences that binge drinking can have on neurodegeneration, including of the amygdala and prefrontal cortex.<sup>21</sup> A meta-analysis published in <i>Addiction Biology</i><sup>22</sup> reviewed white matter volume in patients with alcohol use disorder. Study investigators recommend further research to examine the possibility of white matter recovery “with sustained abstinence.”

Is Alcohol Truly Cardioprotective?

Prevailing evidence suggests that light alcohol consumption can lower a person’s risk of developing cardiovascular disease (CVD). A 2014 scientific review<sup>23</sup> published in the <i>Journal of Cardiopulmonary Rehabilitation and Protection</i> highlighted some lingering questions, including the impact of beverage type — beer, red wine, or hard liquor — on CVD risk reduction. Conversely, the American College of Cardiology recently highlighted results from a meta-analysis showing that regular, moderate, alcohol consumption can lead to an 8% increase in the risk for atrial fibrillation (AF) for every drink consumed per day,<sup>3</sup> contrary to the perception of moderate intake as cardioprotective. Aleksandr Voskoboinik, MBBS, of the Alfred Heart Centre and the University of Melbourne in Melbourne, Australia, and colleagues reviewed the epidemiology and pathophysiology of AF, concluding that cardioprotective benefits don’t apply to patients with AF.<sup>4</sup>

The Obesity Epidemic

The role of alcohol intake in the obesity epidemic is still unclear: according to a review published in <i>Current Obesity Reports,</i><sup>24</sup> the general consensus indicates that light drinking does not increase adiposity, while heavy drinking often results in weight gain. Mixed evidence suggests that drinking before meals may increase food intake, although available studies have only reported results relating to beer and wine consumption. In a similar manner, a study from the <i>European Journal of Clinical Nutrition</i><sup>25</sup> in more than 4700 adults found that after adjustment for age, energy intake, and regular physical exercise, both men and women who consumed more than 60 g and 30 g per day of alcohol, respectively, were more likely to be obese vs non-drinkers.

Mental Health and Substance Abuse

Excessive drinking does not necessarily equal alcohol dependence, according to the CDC.<sup>26</sup> In conjunction with the Substance Abuse and Mental Health Services Administration (SAMHSA), data from more than 138,000 adults who responded to the National Survey on Drug Use and Health (NSDUH) in 2009, 2010, or 2011 were analyzed.<sup>27</sup> According to the results, 90% of excessive drinkers did not meet <i>Diagnostic and Statistical Manual of Mental Disorders</i> (4th edition, DSM-IV) criteria for alcohol dependence. Robert Brewer, MD, MSPH, Alcohol Program lead at the CDC and one of the study’s investigators noted that while the results may be “contrary to popular opinion,” they “emphasize the importance of taking a comprehensive approach to reducing excessive drinking” through evidence-based strategies, screening, counseling, and treatment. Clinicians who are uncertain how the changes from DSM-IV to DSM-5 may affect the diagnosis of alcohol use disorders should reference the NIAAA comparison fact sheet.<sup>28</sup>

HIV and Hepatitis C

Although research has indicated that alcohol consumption can pose significant health risks in patients with HIV and hepatitis C (HCV),<sup>29</sup> not much is known about patient perception of these risks. Multiple studies<sup>30-32</sup> identified skewed perceptions in these patient populations regarding the potential consequences of continued alcohol consumption. For example, patients with HIV/HCV coinfection may underreport alcohol consumption during clinician interviews.<sup>32</sup> Clinicians treating these patients may need to employ innovative rather than standard strategies to emphasize the benefits of a reduction in alcohol intake. Additional challenges have been identified in women living with HIV, many of whom report drinking to self-manage pain or emotions.<sup>31</sup>

Alcohol Use and Dependence in Young Adults

According to the CDC, alcohol is the most commonly used or abused drug in US adolescents and young adults.<sup>33</sup> Multiple studies<sup>34-36</sup> assess the benefits, harms, and efficacy of various interventional strategies used to reduce the frequency of and risks associated with underage drinking. One study<sup>34</sup> found that when comparing direct strategies (eg, “space drinks out over time”) with indirect strategies (eg, “have a designated driver”), direct strategies resulted in less alcohol consumption while indirect strategies resulted in fewer alcohol-related consequences. Additionally, a meta-analysis of 185 studies<sup>36</sup> found that while brief alcohol interventions result in modest but beneficial alcohol-related outcomes, such interventions can be beneficial based on their “brevity and low cost.”

Managing Alcohol Use in Patients

Clinicians play an important role in the treatment of alcohol use disorders. A guide published by the NIAAA<sup>37</sup> notes that regardless of the severity of a patient’s alcohol use, “most people with an alcohol use disorder can benefit from some form of treatment.” Clinicians can regularly screen patients for alcohol use disorder, and resources from the CDC<sup>38,39</sup> and the NIAAA<sup>40</sup> are available for everyday clinical practice.

According to the National Institute on Alcohol Abuse and Alcoholism (NIAAA), 87.6% of people age 18 and older in the United States have consumed alcohol at some point during their lifetime.1 Although some research indicates that alcohol consumption may have a beneficial effect on health,2 other research has found that even moderate alcohol consumption can lead to an elevated risk for developing cardiovascular disease (CVD), among other conditions.3,4

Compiled by Lauren Biscaldi

References

Alcohol facts and statistics. Bethesda, MD: National Institute on Alcohol Abuse and Alcoholism. Updated January 2017. Accessed February 28, 2017.